A Study of Carbureted Motorcycle Exhaust Emissions Using Gasoline-Ethanol Blended Fuels

This paper examines the effect of percentage ethanol blended in gasoline on air-fuel ratio (A/F) and exhaust emissions of a 125 c.c. carbureted motorcycle. Three tests were conducted: subjective assessment of motorcycle performance test, carburetor test, and motorcycle emissions test. Several ethanol-gasoline blended fuels and six carburetor nozzles were used in the study. The motorcycle was tested on chassis-dynamometer by following CNS 11386 standard. In the experiments, the air-fuel ratio and the emissions of carbon monoxide (CO), hydrocarbon (HC), and nitrogen oxides (NOx) were measured and analyzed. The results showed that the motorcycle could be started up as the ethanol concentration no larger than 60%. As the concentration of the ethanol increased, A/F increased 7% and decreased 8% for different carburetors, CO emission decreased, HC emission decreased first then increased further, NOx emission increased first then decreased further as well.